描述：

• 导入header.php文件。
• 如果设置了参数 $name ，则会导入header-{name}.php文件。
• 如果主题文件夹中没有header-{name}.php文件，则导入wordpress默认主题的sidebar.php文件（wp-includes/theme-compat/header.php）。

用法：

<?php get_header( $name ); ?>

参数：

$name

(string) (可选) 调用 header-name.php.

默认值: None

源文件：

/**
 * Load header template.
 *
 * Includes the header template for a theme or if a name is specified then a
 * specialised header will be included.
 *
 * For the parameter, if the file is called "header-special.php" then specify
 * "special".
 *
 * @since 1.5.0
 *
 * @param string $name The name of the specialised header.
 */
function get_header( $name = null ) {
	/**
	 * Fires before the header template file is loaded.
	 *
	 * The hook allows a specific header template file to be used in place of the
	 * default header template file. If your file is called header-new.php,
	 * you would specify the filename in the hook as get_header( 'new' ).
	 *
	 * @since 2.1.0
	 * @since 2.8.0 $name parameter added.
	 *
	 * @param string $name Name of the specific header file to use.
	 */
	do_action( 'get_header', $name );
 
	$templates = array();
	$name = (string) $name;
	if ( '' !== $name )
		$templates[] = "header-{$name}.php";
 
	$templates[] = 'header.php';
 
	// Backward compat code will be removed in a future release
	if ('' == locate_template($templates, true))
		load_template( ABSPATH . WPINC . '/theme-compat/header.php');
}